This invention relates to a method of winding armatures for revolving-field electrical machines and more particularly to an improved winding method that permits a greater coil density to be obtained and avoids the likelihood of damaging the wire by the winding needle during the winding operation.
Various methods have been employed for forming the coil windings for the armature of rotating electrical machines such as motors or generators. Generally these winding methods result in somewhat complicated structures and structures wherein the maximum coil densities are not capable of being obtained. Several of these methods involved passing a needle in the slot between the extending cores of the armature and then having that needle circumscribe the individual cores so as to form the windings. Because of the fact that the needle must be passed in the space between the cores, room must be left for it and this decreases the coil density.
In addition, there is a likelihood that the needle may engage already wound coils and damage them particularly by removing their insulation. These various prior art methods are described in full detail in the co-pending application assigned to the Assignee hereof, entitled xe2x80x9cStator Coil Structure For Revolving-Field Electrical Machine and Method Of Manufacturing Samexe2x80x9d, U.S. app. Ser. No. 09/683764, filed Feb. 12, 2002.
Disclosed in that co-pending application are several ways in which the coil can be wound without necessitating the passage of the winding needle through the slots between adjacent pole teeth. This involves looping the wire around the pole teeth in a lasso type fashion and effecting movement of each winding along the pole tooth toward the circular core of the armature. In order to assist in this pulling action, devices have been provided on the insulating bobbins around which the wire is looped or the end of the wire is held in some fashion at this end of the pole tooth. If the insulator is provided with these projections, then it is necessary to cause movement of the needle to this end of the pole tooth at the side thereof in order to provide the attachment or looping. This somewhat complicates the mechanism and also adds parts unnecessarily to the bobbin.
It is, therefore, a principal object to this invention to provide an improvement in this type of winding arrangement wherein a separate system is provided for positioning the wire ends at the ends of the core portion of the armature to facilitate winding.
It is a further object to this invention to provide an improved apparatus for performing this function.
A first feature of the invention is adapted to be embodied in a method of winding the coils of a rotating electrical machine. In this method, a circular core of magnetic material with a plurality of magnetic pole teeth extending radially from the circular core is provided. Each of the magnetic pole teeth defines a core and slots formed there between. Each of the slots defines a mouth that is formed between adjacent outer ends of the cores. The winding method comprises the steps of positioning a threading needle having an opening through which the wire for the winding of the coils is fed into proximity to one of the mouths. The needle opening is moved in a path around one of the pole teeth and at one side of the slot without moving the needle in any substantial distance along the length of the one pole tooth to form a first winding. A portion of at least the initial winding is restrained at the circular core side of the pole tooth. The movement of the needle opening is continued in a path around the one of the pole teeth at the one side of the slot without moving the needle in any substantial distance along the length of the one pole tooth to form succeeding windings. Each of which in combination with the pulling action of restrained winding portion forces the previous winding along the pole tooth toward the circular core without requiring movement of the needle in any substantial distance along the length of the one pole tooth so that the needle not be moved any substantial distance into the slot.
A further feature of the invention is adapted to be embodied in an apparatus for performing the aforenoted method of winding the coils of a rotating electrical machine. In this apparatus a threading needle having an opening through which the wire for the winding of the coils is fed is provided. A drive is provided for moving the needle opening in a path around one of the pole teeth and at one side of the slot without moving the needle in any substantial distance along the length of the one pole tooth to form a first winding. A restraining mechanism restrains a portion of at least the initial winding at the circular core side of the pole tooth so that when movement of the needle opening is continued in a path around the one of the pole teeth at the one side of the slot without moving the needle in any substantial distance along the length of the one pole tooth to form succeeding windings the pulling action of restrained winding portion forces the previous winding along the pole tooth toward the circular core without requiring movement of the needle in any substantial distance along the length of the one pole tooth so that the needle not be moved any substantial distance into the slot.